This invention relates to oil and gas industry and, more particularly to an apparatus for moving elongated tubular members between a rack and a rig floor.
During drilling and completion operations, it is necessary to make up and/or break down long strings of tubular members such as drill pipe and casing. The string of pipe may be thousands of feet long, and it is therefore necessary to transport pipe joints, which can be up to 32 feet long, from a pipe rack located away from the rig up to the rig floor. When the drill string is tripped out of the hole, the string of pipe is broken down into separate joints and returned to the pipe rack. The drilling platform is usually at some distance from the pipe rack and is elevated above the ground by 15-20 feet.
The handling of oil well pipe is one of the most dangerous jobs on a drilling rig. Some of the pipe joints weigh thousands of pounds, and it is difficult to move the pipe from a horizontal position on the pipe rack into a vertical position overlying the borehole in the rig. The industry has developed various types of equipment to assist in transporting the pipe segments from the pipe rack to the platform and back to the pipe rack. Conventional pipe handling machines use a trailer, a carriage mounted on the trailer and a trough, which is supported by the carriage. The operators load one pipe segment at a time into the trough from the pipe rack. A lift arm moves the carriage to elevate one end of the trough to a platform floor, where rig operators use pick up arms to slide the pipe segment from the trough and lower the pipe segment into the borehole.
Even though part of the pipe handling process is assisted by the elevating carriage, the operators still need to manually lift the pipe segment from a horizontal pipe rack and carefully place it in the trough of the pipe handling machine. It is important to note that the exterior of the pipe segments has a protective anti-corrosive coating, which can be damaged if the pipe segment is dropped or scraped against an edge of the trough. In conventional equipment, the trough is affixed to the elevating arms and does not pivot or tilt.
U.S. Pat. No. 7,665,944 teaches a pipe handling method, which uses a longitudinally extending base frame assembly having a system of base rails or tracks, a movable carriage having a carriage frame and roller assembly for supporting the movable carriage on the frame base rails, and a pipe lifting structure that is mounted to this movable carriage. The carriage, and consequently the pipe lifting structure, is configured so that it may be moved as desired along the length of the base frame by means of the carriage rollers and base rail system to facilitate a desired lifting sequence. The pipe lifting structure has a semicircular pipe support trough that is supported by hydraulically driven telescopically extendable lifting arm assembles. The base end of each telescopically extendable lifting arm assembly is pivotally mounted to the carriage. The trough end of each lifting arm assembly is pivotally mounted to a lifting structure stabilizer frame that extends longitudinally between each lifting arm assembly. According to the '944 patent, the pipe trough is raised by the second end of the first lifting arm; then the lifting arm is extended telescopically without extending the length of the other lifting arm assembly; and then the length of pipe is removed from the pipe trough by pivoting the pipe trough transversely with respect to the base frame.
While the method of U.S. Pat. No. 7,665,944 may work satisfactory in many circumstances, there remains a need for a pipe handling machine that would facilitate movement of the pipe segments from the pipe rack into the trough and further increase safety of the pipe handling process.
The present invention contemplates elimination of drawbacks associated with conventional methods and provision of a pipe handling apparatus and method that assists in moving pipe segments from and to the pipe rack and moving the pipe trough toward the derrick.